This invention relates to roadside barriers of the type having an elongated container configured to receive and hold a volume of fluent material, wherein the container includes a pair of sidewalls having sufficient rigidity to allow the container to stand alongside a roadway and sufficient resilience to deform upon an impact by a vehicle and to recover their shape after at least some impacts.
U.S. Pat. No. 4,681,302 to Thompson, assigned to the assignee of the present invention, describes an energy absorbing roadside barrier of the type described above. The disclosed barrier includes a water filled plastic container that defines an array of ridges and channels along each side. Adjacent barriers are interconnected by overlapping mounting elements which receive vertically oriented pins.
The water contained by the barrier provides mass while allowing the barrier to deform in an impact. The sidewalls of the barrier are shaped to reduce friction with the tire of an impacting vehicle, and the plastic material from which the barrier is formed is selected to have a low coefficient of friction. These features combine to reduce the tendency of an impacting vehicle to climb the barrier during the impact.
Actual testing has shown the barrier described in the above-identified Thompson patent to be effective in many applications. However, the disclosed barrier does have certain drawbacks. Since the container itself utilizes plastic materials to define the structure of the container, such barriers have in the past been formed of relatively expensive plastic materials such as cross linked polyethylene. Even when such expensive materials are used, the length of the barrier has been limited, to 5 feet in one example. This increases the number of barriers required for any particular application, and the overall cost. The weight of the barrier when empty should be kept as low as possible to facilitate use.
Accordingly, it is an object of this invention to provide an improved energy absorbing barrier which is light in weight, and which can be built at lower cost using less expensive materials that allow a barrier of greater length to be used.